Stroke or Vestibular Neuritis? Use the HINTS

The other day, Tom and I had a patient with the symptom of continuous vertigo. This is to be distinguished from someone with episodic triggered vertigo, such as when turning their head to the right, which we associate with benign paroxysmal positional vertigo (BPPV). The differential for continuous vertigo includes vestibular neuritis (a relatively benign diagnosis, the “Bells Palsy of Cranial Nerve 8”) and posterior circulation stroke (a potentially lethal disease if missed).

And as deus ex machina, Johnathan Edlow published an article on just this subject.

He believes the old teaching is failing us. We were taught to first ask “dizziness means different things to different people” to distinguish lightheadedness from ataxia from vertigo. If it was was to differentiate central from peripheral by using a constellation of symptoms: sudden or insidious onset, vomiting or not, severity of vertigo. The problem is, patients cannot make the distinction between vertigo and lightheadedness reliably and those distinguishing symptoms are all very insensitive.

So Edlow presents a different approach: timing and triggers.

Acute Vertiginous Syndrome (AVS): vertiginous symptoms that lasts days, is continuous and may be accompanied by nausea, vomiting and change with motion. This is not BPPV.

Our patient suffered from AVS. The HINTS exam has been shown to be even more sensitive the MRI in distinguishing between vestibular neuritis and a posterior circulation stroke.

The Anatomy

Pictured here is an actual photograph from a meticulous dissection. The thing that matters is that the cochlea (responsible for hearing) and vestibular apparatus (responsible for balance) are supplied by the vestibular and cochlear nerve, which come from the vestibulo-cochlear nerve. Both are supplied by the anterior inferior cerebellar artery, part of the posterior circulation. Occlusion of this artery can lead to balance and hearing changes as well as edematous cerebellar strokes that herniate. Hence it’s important to be able to distinguish the cause of acute vertiginous symptoms.

Inflammation of the vestibular nerve leads to vestibular neuritis. Inflammation of the vestibulo-cochlear nerve leads to labyrinthitis.

The Five Questions You Need to Ask in AVS

There are five questions you need to ask in order to distinguish between this central and peripheral cause.

Is there central nystagmus?

Is there skew deviation?

Is the head impulse test negative in a patient with nystagmus?

Are there any CNS signs on exam?

Any gait or truncal ataxia?

If you answer yes to any of these questions, evaluate for a central cause. If all are no, it’s likely vestibular neuritis. These questions will take us through the HINTS exam, but we don’t perform the exam in the order of the letters H-I-N-T-S, instead it’s N – TS – HI. But that doesn’t spell anything.

1. Is there central nystagmus?

First we should talk about nystagmus, the “n” in HINTS. These are the quick saccade movements that occur in patients with vestibular issues. There is a fast followed by slow movement and the nystagmus is named for the direction of the fast component. No nystagmus is considered normal.

Now have the patient look to the left and right. It may be necessary to hold a piece of paper to the side so the patient isn’t looking at anything in particular (which can extinguish nystagmus).

Here you can see that when the patient is looking to the left (top drawing), there is a fast component to the right followed by slow to the left.

When the patient looks to the right (bottom drawing), there is a fast component to the right followed by slow to the left.

This is unidirectional nystagmus. Contrast this with bi-directional nystagmus.

Here you can see that when the patient looks to the left, there’s a fast to the right followed by slow to the left.

When the patient looks to the right, there’s a fast to the left followed by a slow to the right.

The fast and slow components change direction when the patient looks in different directions.

Type of nystagmus

What’s it mean?

No nystagmus

normal state… though you can sometimes see this with a cerebellar stroke. Great.

Spontaneous horizontal nystagmus

not diagnostic

Gaze evoked horizontal nystagmus

not diagnostic, though probably BPPV

Direction changing horizontal nystagmus

Central cause

Vertical nystagmus

Central cause

Torsional nystagmus

Central cause

Nystagmus if the first thing to look for.

2. Is there skew deviation?

The next question to ask is if the eyes deviate upward and downward when you cover and uncover it. You are looking for small deviations so look first at one eye, cover and uncover both. Then look at the other eye, cover and uncover both.

Tell the patient to focus on your nose.

Cover one of the patient’s eyes

Uncover it and look for an upward deviation. It may be as small as 1 mm.

Cover the other eye. The patient is still looking ahead.

Uncover that eye and that eye may deviate downward 1 mm.

3. Is there head impulse in a patient with nystagmus?

Tell the patient to relax their head and focus on your nose. Then gently rotate the head left and right about 10-15° then quickly bring them back to center.

Normal is no saccade. This is what you would expect in a patient without nystagmus, so if the patient demonstrates no nystagmus in the first step, you do not progress further and get to this step.

If there is a saccade in a patient with vertigo, this represents a peripheral lesion.

Lack of vertigo in a patient with vertigo represents a central problem. So a “normal finding in a patient without vertigo” is the same as an “abnormal finding in a patient with vertigo.”